[Openstack] OVF vs. bare container formats for qcow2 images

Adam Young ayoung at redhat.com
Sat Jun 30 01:53:01 UTC 2012


On 04/01/2012 11:15 AM, Lorin Hochstein wrote:
>
>
> On Mar 29, 2012, at 12:40 PM, Daniel P. Berrange wrote:
>
>> On Wed, Mar 28, 2012 at 04:41:28PM -0400, Lorin Hochstein wrote:
>>> All:
>>>
>>> Given that I have a qcow2 image from somewhere (e.g., downloaded
>>> it from a uec-images.ubuntu.com <http://uec-images.ubuntu.com>, 
>>> created one from a raw image using
>>> qemu-img) that i want to add to glance:
>>>
>>> 1. How can I tell whether it's an "ovf" or "bare" container format?
>>
>> You are mixing up terminology here. Disk image formats are things like
>> raw, qcow2, vmdk, etc.
>>
>> OVF refers to the format of a metadata file provided alongside the
>> disk image, which describes various requirements for running the
>> image.
>>
>> The two are not tied together at all, merely complementary to
>> each other.
>>
>
> Thanks, that clears things up. I was confused by this language, which 
> sounded to me like the metadata was embedded in the disk image file:
>
> http://glance.openstack.org/formats.html
>
> "The container format refers to whether the virtual machine image is 
> in a file format that also contains metadata about the actual virtual 
> machine."
>
> In addition, the docs have examples like this, which clearly aren't 
> meaningful:
> http://glance.openstack.org/glance.html#important-information-about-uploading-images

Just to add to the confusion  the OVF can contain both the metadata file 
and the disk image file in a single archived file.

"An OVF package consists of several files, placed in one directory. A 
one-file alternative is the OVA package, which is a TAR file with the 
OVF directory inside."

http://en.wikipedia.org/wiki/Open_Virtualization_Format#Technical_description


I think that what you are reading above refers to the single file 
alternative.
>
>
> $> glance add name="My Image" is_public=true \
>       container_format=ovf disk_format=raw < /tmp/images/myimage.iso
>
> I'll propose a change to the docs for that.
>
>>
>>> Whenever I add a qcow2 image to glance, I always choose "ovf",
>>> even though it's probably "bare", because I saw an example
>>> somewhere, and it just works, so I keep doing it. But I don't
>>> know how to inspect a binary file to determine what its container
>>> is (if "file image.qcow2" says it's a QEMU QCOW2 Image (v2), does
>>> that mean it's "bare"?). In particular, why does the user need to
>>> specify this information?
>>
>> If you simply have a single  someimage.qcow2 file, then you simply
>> have a disk image. Thus there is no OVF metadata involved at all.
>>
>> eg, this is the (qcow2) disk image:
>>
>> http://uec-images.ubuntu.com/precise/current/precise-server-cloudimg-amd64-disk1.img
>>
>> While this is an OVF metadata file that optionally accompanies the 
>> disk image
>>
>> http://uec-images.ubuntu.com/precise/current/precise-server-cloudimg-amd64.ovf
>>
>
> Gotcha.
>
>
> It's not clear to me how you would specify the OVF metadata file when 
> adding an image file to glance.
>
>
> Take care,
>
> Lorin
> --
> Lorin Hochstein
> Lead Architect - Cloud Services
> Nimbis Services, Inc.
> www.nimbisservices.com <https://www.nimbisservices.com/>
>
>
>
>
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